Volunteers who patrol California beaches for plastic, cigarette butts and other litter will be on the lookout this winter for flotsam from last year's monstrous tsunami off Japan's coast.

Armed with index-size cards, beachcombers will log water bottles, buoys, fishing gear and other possessions that might have sailed across the Pacific to the 1,100-mile shoreline.

The March 2011 disaster washed about 5 million tons of debris into the sea. Most of that sank, leaving an estimated 1 1/2 million tons afloat. No one knows how much debris - strewn across an area three times the size of the United States - is still adrift.

Tsunami flotsam has already touched the Pacific Northwest and Hawaii this year. The West Coast is bracing for more sightings in the coming months as seasonal winds and coastal currents tend to drive marine wreckage ashore.

Like the past winter, scientists expect the bulk of the debris to end up in Alaska, Washington state, Oregon and British Columbia. Last week, the Coast Guard spotted a massive dock that possibly came from Japan on a wilderness beach in Washington state.

Given recent storm activity, Northern California could see "scattered and intermittent" episodes, said Peter Murphy, a marine debris expert at the National Oceanic and Atmospheric Administration, which recently received a $5 million donation from Japan to track and remove tsunami debris.

To prepare, state coastal regulators have launched a cleanup project to document possible tsunami items that churn ashore. Working with environmental groups, volunteers will scour beaches with a checklist. It's like a typical beach cleanup, but the focus will be to locate articles from Japan.

Until now, efforts in California have been haphazard. The goal is to organize tsunami debris cleanups at least once every season stretching from the Oregon state line to the Mexican border and then posting the findings online.

Debris from Asia routinely floats to the U.S. It's extremely difficult to link something back to the Japanese tsunami without a serial number, phone number or other marker.

Of the more than 1,400 tsunami debris sightings reported to NOAA, the agency only traced 17 pieces back to the event, including small fishing boats, soccer balls, a dock and a shipping container housing a Harley-Davidson motorcycle with Japanese license plates. No confirmed tsunami debris so far has reached California.

Even in the absence of a direct connection, California coastal managers said it helps to know if a beach is being covered with more marine debris than usual.

"We want to get an idea of where to focus our efforts. We have limited resources," said Eben Schwartz, marine debris program manager at the California Coastal Commission, which heads the $50,000 NOAA-funded project. "If we see the problem is hitting the north coast and not getting as far south as San Francisco, that tells us where to focus."

Last summer, NOAA awarded $250,000 to five West Coast states to help with tsunami debris removal. Alaska spent its share to clean up a 25-mile stretch of beach before the weather turned too bitter. Hawaii and Washington state have yet to dip into their funds.

Oregon racked up $240,000 to remove debris on beaches including a 66-foot dock that broke loose from the port of Misawa during the tsunami and splashed ashore over the summer. Part of the tab - $50,000 - was covered by NOAA.

Charlie Plybon, Oregon's regional manager at the Surfrider Foundation, said the tsunami has raised beachgoers' awareness about marine debris plaguing the world's coastlines.

"There's a bit of tsunami debris fever. It's like an Easter egg hunt," said Plybon, who has been cleaning up the Oregon coast for more than a decade. "People used to walk past debris. Now they want to be engaged."

Health experts have said debris arriving on the West Coast is unlikely to be radioactive after having crossed thousands of miles of ocean. Tsunami waves swamped a nuclear power plant and swept debris into the ocean. The debris field, which once could be spotted from satellite and aerial photos, has dispersed. More than 18,000 residents were killed or went missing.

Volunteer Julie Walters has combed Mussel Rock Beach south of San Francisco for wreckage, but all that's turned up so far are wave-battered boat parts and lumber of unknown origin.

If she did find an object with a direct link, "I would find it quite intriguing that it made this incredible journey across the Pacific," said Walters, a volunteer with the Pacifica Beach Coalition. "It would also sadden me to think of the human tragedy."

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AP writers Becky Bohrer in Honolulu and Tim Fought in Portland, Ore., contributed to this report.